This research is directed toward the elucidation of the mechanisms of phosphate condensations and esterifications as mediated by reagents commonly used in the chemical synthesis of polynucleotides and nucleotide co-factors. Typical reagents are p-toluene-sulfonyl chloride, dicylohexylcarbodiimide and trichloroacetonitrile. It is proposed that this can be accomplished by following the time-courses of the reactions through use of phosphorus-31 nuclear magnetic resonance spectroscopy and through use of selected phosphonate analogs of the phosphates. A second objective is to develop methods whereby organophosphorus compounds in various biological systems can be identified and their reactions followed by phosphorus-31 nuclear magnetic resonance spectroscopy.